The electrolytic cell is of particular importance in recovery of copper from copper bearing ores and concentrates as described in U.S. Pat. No. 4,061,552 and the recovery of lead from lead bearing ores and concentrates as described in U.S. Pat. Nos. 4,148,698 and 4,381,225.
In these processes not only are electrodes and electrolyte involved but also two lots of solids, the metal bearing ore or concentrate and the particulate metal product. To achieve a maximizing of reaction with resultant high yield it has been previously believed the anode and cathode should be in close parallel relationship. Illustrative of this general belief can be seen in Australian Pat. No. 292,235 where considerable emphasis is given to a design which preserves a parallel relationship.
Also typical of the conventional electrolytic cell is the use of diaphragm bags surrounding the cathode. A multiplicity of diaphragm bags is employed to keep slurry away from the cathodes where clean metal is required to be deposited. Some problems experienced in the operation of such a cell include:
(1) Clogging of the diaphragm materials with particles when high hydraulic gradients must be used in the cell to maintain a uniformity of agitation of the slurry.
(2) Difficulties in trying to maintain large areas of cloth in parallel planes without distortion, which is particularly aggravated by high hydraulic gradients in the cell. In most cases it is undesirable for the cloth to come in contact with
(3) The energy requirements resulting from the necessity for agitation in the bottom of the cell to maintain adequate suspension of the mineral between the bags.
Other problems include:
Difficulties in recovering the metal powder if it falls off the electrodes into the cell floor or the bags, or difficulties and costs in removing and stripping the electrodes if the metal particulate adheres strongly.
To overcome these problems it has been known to introduce additives into the electrolyte which inhibit the growth of dendrites of metal powder on the cathode. Further, many attempts have been made to provide a simple and effective recovery of metal powder. However the very design of parallel cathode relationship complicates recovery. In particular, previously it has not been possible to integrate a central recovery system, especially with diaphragm cells, without complex pipework and flushing techniques.
The present invention includes apparatus which overcomes these problems and in addition provide cells which are relatively inexpensive, long lasting and allow greatly increased efficiency of operation. Also provided is apparatus for the removal of products such as the metal powder products according to U.S. Pat. No. 4,061,552 for copper and U.S. Pat. Nos. 4,148,698 and 4,381,225 for lead.
The methods the subjects of U.S. Pat. No. 4,061,552 and U.S. Pat. Nos. 4,148,698 and 4,381,225 and the apparatus of this patent application provide a unique combination of a slurry of minerals of metals including copper, lead, silver, zinc, bismuth, gold, nickel and cobalt in electrolyte, and extraction of one or more of the valuable metals from the electrolyte by electrolytic means. The system operates at atmospheric pressure, at temperatures below the boiling point of the electrolyte, and with no exotic or costly reagents or materials and no close tolerances.